Diaphragm switch for electric continuous-flow heaters



L. SCHOMANN Sept. 4, 1962 DIAPHRAGM SWITCH FOR ELECTRIC CONTINUOUS-FLOW HEATERS Filed Dec. 15, 1958 INVENTOR.

United States Patent 3,052,776 DIAPHRAGM SWITCH FOR ELECTRIC CONTINUOUS-FLOW HEATERS Leonid Schumann, Langenberg, Rhineland, Germany, assignor to Alfred Eckerfeld, Essen (Ruhr), Germany Filed Dec. 15, 1958, Ser. No. 780,469 Claims priority, application Germany Dec. 14, 1957 7 Claims. (Cl. ZOO-81.9)

This invention relates to a direct action diaphragm switch for flow-controlled electric heaters. When a tap (faucet) is opened, differential pressure on the diaphragm causes a contact spring to be actuated directly (not through a snap action mechanism) through a transmission member in order to connect a heating coil. With known direct action diaphragm switches of this kind, the motion of the diaphragm is transmitted to the contact spring and the latter spring is caused to make contact against the action of its own spring force. For these an exact adjustment of the contact parts is necessary. Furthermore, the operational contact pressure to be -main tained is dependent on the motion of the diaphragm. Fluctuations inthe pressure or differential pressure effecting the diaphragm procure a change in the contact pressure.

In accordance with the present invention substantially more favorable conditions can be achieved in such direct action diaphragm switches in that the switch is closed uniformly by its own spring pressure, while with the contact open the contact spring is maintained under spring pressure by the transmission member supported by the diaphragm.

The use of a prebent rigid diaphragm is especially desirable, for it springs from one extreme position to the other when predetermined pressure is exceeded. In this Way an instantaneous switching is achieved without any supplementary mechanism. Lost motion in the switch operating mechanism prevents affecting the contact pressure.

The contact spring when switched off can be provided also with locking handle so that switching on of the heating power does not take place even though the transmission member of the diaphragm switch releases the contact spring. The same lost motion feature allows the diaphragm to operate without being hindered in its movement through the locked contact spring.

In the further development of the invention, a transmission member controlled by the diaphragm extends through the wall of the diaphragm switch casing to which it is sealed by means of an elastic plastic tube, one end of which is pushed over a collar of the transmission member and the other end of which is pushed over a bushing provided on the wall. If, as seen in FIG. 4, the transmission member, like a tappet, extends in the direction axial of the diaphragm, the sealing plastic tube is under compression strain. As shown in FIG. 1, however, a transmission member is used that extends transversely to the diaphragm motion, and the plastic scealing tube also serves as a hinged connection between the transmission member and th diaphragm switch casing so that any metallic hinge connection is superfluous. In this manner diaphragm switches are produced which are simple and easy to manufacture in their mechanical structure but which at the same time are reliable and operate with a high degree of operational efficiency.

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In the preferred forms of the invention, great simplification has been achieved by combining the diaphragm switch with the body of the heater it controls using the base body of the heater to complete one diaphragm chamber, and to provide passages leading to both diaphragm chambers.

Two preferred embodiments are described in more detail in the following detailed description where reference is made to FIGS. 1 to 4 in the accompanying drawmgs.

FIGURE 1 is a continuous-flow heater with diaphragm switch shown in sectional side view taken on line 1-1 of FIG. 2.

FIGURE 2 is a front view of the continuous-flow heater.

FIGURE 3 shows a section 33 of FIG. 2, and

FIGURE 4 is a continuous-flow heater with a diaphragm switch of an alternative design shown in sectional side elevation.

In the embodiment shown in FIGS. 1 to 3, there are mounted on a base element 1 manufactured from insulating plastic, two contact springs 3, 3' which are mechanically connected through an insulation bridge.

The contact springs 3, 3', owing to the action of their own spring force tend to make contact with the counter contacts 4, 4 which are likewise mounted on the base element 1. They may be restrained from this by the transmission member 5 of a diaphragm switch 6. Transmission member 5 bears on but may move from the insulation bridge 2.

The casing or cover 6 of the diaphragm switch 6 is shaped in box form and has a sealing ring 6" which lies on a surface of the base element 1 so that cover 6 forms a shell over the diaphragm 7. By simplified use of a preformed metal diaphragm 7, the two diaphragm chambers 8, 9 are economically provided. One of these, being designated by numeral 8, is formed in part by the heater base 1. Thus it lies between the base element 1 and the diaphragm 7. The surface of base 1 need not be machined. It can be fiat, as shown relying on sealing ring 6" to provide the chamber depth to the extent needed. The other diaphragm chamber 9 lies bctween the diaphragm 7 and the casing or shell 6. The diaphragm chamber 9 is connected through a channel 10 (FIG. 3) to an inlet passage 11 (FIG. 2) of the base element so that in the diaphragm chamber 9 the unthrottled pressure of the inflowing cold water is effective. The diaphragm chamber 8, on the other hand, is connected through a channel 12 (FIG. 1) to the discharge pipe 13 (FIG. 2) of the base element 1. Channels 10 and 12 ar formed, at least in part, by the base body 1 in which the main passages 11 and 13 are also formed, hence no labor or material expense is required in making connections in assembly. By means of a constriction such as a throttle screw 14 (FIG. 2) which throttles the water flowing through the base element I, a dynamic pressure difference is produced by the passage of the Water; that is, a lesser pressure is effective during the water passage in the diaphragm chamber 8 than in the diaphragm chamber 9. The result of this is that the diaphragm 7 which is normally curved outwards suddenly curves in reverse direction as soon as Water flows through the base element 1 upon the opening of a tap valve. With the tap valve closed there is, naturally, a pressure equalization in the diaphragm chambers 8 and 9 whereby the diaphragm 7 is curved outwards by its own spring force. The headpiece 15 of the transmission member is supported by the diaphragm 7. A flexible plastic tube 16 is drawn over a collar of this headpiece on the one side, and on the other side over a bushing 17 which is inserted into the wall of the diaphragm switch casing 6'.

This plastic tube 16 serving for the sealing bushing of the transmission member 5 simultaneously serves as a hinged connection between the transmission member 5 and the diaphragm switch casing 6. The headpiece of the transmission member 5 is urged toward contact with the diaphragm through the action of the contact springs 3, 3'. As soon as there is a flow of water and the diaphragm 7 springs into the inner position, the transmission member 5, 15 is able to follow so that the contact springs 3, 3' are able to make contact with the counter contacts 4, 4- under the influence of their own spring force, whereby the heating current of the apparatus is switched on. The contact pressure between the contact springs 3, 3 and their counter contacts 4, d is quite independent of any fluctuations in pressure in the water section occurring during operation.

By means of a handle 18 which acts on the insulation bridge 2, the contact springs 3, 3' may be locked in the switched-off position if it is required that any switching on of the heating power be avoided when the diaphragm switch 6 responds, e.g., in order to tap cold water. With the insulation bridge 2 locked, the diaphragm 7 and the transmission member 5, 15 are able to move in the same way as for switch movements when water is flowing, without being hindered by the locking of the spring contacts 3, 3. In other words, the connections between diaphragm '7 and contact spring 3 have lost motion characteristics.

In the embodiment shown in FIG. 4 there lies on the diaphragm 7 of the similarly connected diaphragm switch an axial operating tappet 19 having the function of a transmission member. The tappet 19 is led outwards through a collar 21 of the diaphragm switch casing and lies on a switch lever 23 seated at 22. The pretensioned contact springs 3, 3 are supported by the switch lever 23 engaging the insulation bridge 2. An elastic plastic tube 24 under compression strain serves for sealing the tappet 19 and which is drawn on the one side over the collar of the tappet and, on the other side, over the bushing 21. As soon as overpressure occurs in the diaphragm chamber 9 owing to the flow of water, the preformed diaphragm 7 springs into its inner position so that the tappet 19 can follow, whereby the compressed plastic tube extends. The contact springs 3, 3 then, as a result of their own springiness, close the contacts 3, 4, 3', 4- whereby the heating current is switched on. Heating of the flowing water is achieved in heating element 25 which is insertable into the base element 1 and therefore easily exchangeable, and which incorporates heating coils which are not represented in the drawing.

I claim:

1. A diaphragm switch comprising switch means, a transmission member and a diaphragm positioned for exerting thrust on said transmission member, a wall forming with the diaphragm a pressure chamber and having an inwardly extending collar, said transmission member extending through the collar and the wall, and an elastic sealing tube within the pressure chamber having one end pushed over a fitting portion of said transmission member the other end pushed over and fitting said collar, said transmission member extending transversely to the diaphragm motion, and said elastic tube acting simultaneously as a seal and as a hinged connection between said wall and said transmission member.

2. A diaphragm switch comprising switch means, a transmission member and a pressure responsive actuator positioned for exerting thrust on said transmission memher, a wall forming with the actuator a pressure chamher and having an inwardly extending collar, said transmission member extending fioatingly through the collar and the wall, and an elastic sealing tube within the pressure chamber having one end pushed over a fitting portion of said transmission member the other end pushed over and fitting said collar serving to position the transmission member while yielding to permit its movement by the actuator.

3. A diaphragm switch for flow-controlled electric heaters comprising a diaphragm, having means forming pressure chambers on opposite sides of the diaphragm and having passages for connecting said pressure chambers to sources of differential pressure, a countercontact and a contact spring biased toward the countercontact for switching on a heating coil, and direct action operating means including a transmission member for moving the contact spring away from the countercontact by direct action thereon and actuated by said diaphragm; said operating means having lost motion characteristics allowing the diaphragm to recede, the same as for allowing the spring contact to close, independently of the spring contact position; and means operable by external control for locking the contact spring away from the countercontact.

4. A diaphragm switch for flow-controlled electric heaters comprising a diaphragm, having means forming pressure chambers on opposite sides of the diaphragm and having passages for connecting said pressure chambers to sources of differential pressure, a countercontact and a contact spring biased toward the countercontact for switching on a heating coil, and direct action operating means including a transmission member for moving the contact spring away from the countercontact by direct action thereon and actuated by said diaphragm; said operating means having lost motion characteristics allowing the diaphragm to recede, the same as for allowing the spring contact to close, independently of the spring contact position; said diaphragm operating with snap action from a position in which it allows the spring contact to bear on the countercontact with its full resilient force to a position in which it moves the spring contact away from the countercontact.

5. A switch for flow-controlled electric heaters comprising a pressure responsive means responsive to differential pressure, a countercontact and a contact spring biased toward the countercontact for switching on a heating coil, and direct action operating means including a transmission member for moving the contact spring away from the countercontact by direct action thereon and actuated by said pressure responsive means; said operating means having lost motion characteristics allowing the pressure responsive means to recede, the same as for allowing the spring contact to close, independently of the spring contact position; and means operable by external control for locking the contact spring away from the countercontact.

6. A flow-controlled electric water heater including a base element including a heater chamber, forming inlet and outlet passages for said chamber, and having a surface cooperating with a diaphragm sealed across it, a diaphragm sealed across said surface to form with it a diaphragm chamber, a shell sealed across the diaphragm and forming with it a second diaphragm chamber, and a switch controlled by the diaphragm for connecting a heater for heating water in the heater chamber; said base element also forming passages for connecting the inlet and outlet passages with different ones of said diaphragm chambers.

7. A flow-controlled electric water heater according to claim 6 including a sealing ring spacing the periphery of the diaphragm from the surface of the base element, said surface being fiat.

(References on following page) References Cited in the file of this patent UNITED STATES PATENTS Erickson Aug. 7, 1945 Wilson Jan. 1, 1946 5 Wagner Aug. 12, 1947 Grupp Nov. 14, 1950 Bunklin Jan 29, 1952 Rabinow May 13, 1952 M11161 Oct. 4, 1955 10 6 Riley Feb. 7, 1956 Kayuha June 19, 1956 Zeller Aug. 14, 1956 Booth Apr. 23, 1957 Haberland June 11, 1957 Reed Sept. 16, 1958 FOREIGN PATENTS Germany July 10, 1958 

